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Odb Scanner P1656 Ocv Circuit Is300 2002


zak1234
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I had a ODB reading done on my 2002 IS300 at a nearby Autozone today and I got two error codes P0500 for Speed Sensor and P1656 OCV circuit(Bank 1). My Trac OFF light blinks in the dash all the time, but car drives fine. Does anyone know how I can go about diagnosing this? any circuit digrams or parts I should run OHM meter against?

thanks for your assistance!

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Well, the P0500 DTC is a "No signal fron=m speed sensor "A". for the Skid control ECU. That's the sensor off the rear of the tranny. Probably needs to be replaced because it's a no signal DTC code, and not on of the intermitten or corrupt signals.

The P1656 DTC is I think actually a D 156 DTC off the 02 sensor Heater control, bank 1 sensor 1, or it's the OCV sensor in the ECM.

There is a TSB on the heater control bank 1 sensors though. So that's probably the issue.

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would any Lexus dealer cover that under it since my car is a 2002 ? I've diagnosed the two 02 sensors in the engine bay both are between 11 when cold and full warmed up at 15.5 to 16. I replaced the OCV valve too that sits on top with a used one.

Well, the P0500 DTC is a "No signal fron=m speed sensor "A". for the Skid control ECU. That's the sensor off the rear of the tranny. Probably needs to be replaced because it's a no signal DTC code, and not on of the intermitten or corrupt signals.

The P1656 DTC is I think actually a D 156 DTC off the 02 sensor Heater control, bank 1 sensor 1, or it's the OCV sensor in the ECM.

There is a TSB on the heater control bank 1 sensors though. So that's probably the issue.

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Not sure, as your out of the warranty, but I would call them and see if they may discount it or something.

Cold, you should read 11-16 and warmed up you should read 26-32. So the sensor is bad and needs to be replaced.

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I checked all 3 of my O2 Sensors, each harness has 4 wires, I check each of the two top black wires on each harness. using my volt meter, I set it to ohms, I warmed the car up a little then I checked. they are all at 13.4-13.5 now. If I warm it up more it'll go up higher to 16, but didn't push it. My car starts up without issues, accelerates without issues. wouldn't I have acceleration or starting issues if my 02 were bad? let me know if I should check again when its fully cold(currently ambient weather is low 50f here midwest). I guess I could also disconnect one harness, connect an ohm meter, start the car and let it warm up and see how far the ohm numbers climb

thanks!

Not sure, as your out of the warranty, but I would call them and see if they may discount it or something.

Cold, you should read 11-16 and warmed up you should read 26-32. So the sensor is bad and needs to be replaced.

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one other thing that happens too is this. If I disconnect the battery for 5 minutes, reconnect the check engine light goes away. I warmed up the engine, no check engine light. I put it in drive, started to drive it didn't automatically shift from 1st to 2nd till AFTER check engine light went on then it shifts from 2nd to 3rd and 4th as normal. Check engine light is still on.

not sure if this means much at all. Not sure if I should buy three 02 sensors since all of them read the same ohms 11-16 when cold or if its a different issue here?

it almost seems like I need to test this Cold and Hot or should I just test it when its fully hot(running or off) any ideas here?
I haven't heard of the heater sensor causing any engine running issues, as I think it mainly monitors the cats.

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when you disconnect the battery, it clears the ecu and resets the dtc codes. Then the ecu rerecieves the codes from the sensor and throws up the cel again.

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Ok this morning i performed an ohm test on the two front 02 sensors on my IS300. It was 49F outside and both O2 sensors up front read 13.0(engine cold). I then started the car, fully warmed it up, temp guage was dead center. with the engine running, I performed another read of 17.8 on both sensors up front. Not sure what to make of this since in the book it shows 23-32 warm and 11-16 cold. Is it possible that at idle temps aren't near 1472F to reach anywhere near 23+ ohms.

service book temps 02 sensors:

[11-16] - when its 68F

[23-32] - when its 1,472F

ALSO the manual shows test against terminals +B and HT. are the +B and HT wire colors and which? on the 02 Harness their are four leads -the top leads has black wires, the bottom leads is white and the other lead is blue.

I took it to Autozone to get another scan done, it came up as P0500 "Speed Sensor" sales rep says two sensors on the transmission maybe bad $85each to replace. not sure how its now going from 02 sensor to speed sensor.

when you disconnect the battery, it clears the ecu and resets the dtc codes. Then the ecu rerecieves the codes from the sensor and throws up the cel again.
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